12 <concept id="GUID-C21BB0E4-7AF7-58E5-AAD6-8CE67399460C" xml:lang="en"><title>MessageQueue

    12 <concept id="GUID-C21BB0E4-7AF7-58E5-AAD6-8CE67399460C" xml:lang="en"><title>MessageQueue Example</title><shortdesc>This example application shows the use of message queue

    13 Example</title><shortdesc>This example application shows the use of message queue in interprocess

    13 in interprocess communication using the RMsgQueue class.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 communication using the RMsgQueue class.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <section id="GUID-ED679CA7-FF4C-4E69-8663-5DA46A3D94F4"><title>Download</title> <p>Click on the following link to download the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-d72e85ad-4659-4f66-9cb3-f084e9505709.zip" scope="external">MessageQueueExample.zip</xref>.</p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-d72e85ad-4659-4f66-9cb3-f084e9505709.html" scope="peer">browse</xref> to view the example code.</p> </section>

    15 <section id="GUID-ED679CA7-FF4C-4E69-8663-5DA46A3D94F4"><title>Download</title> <p>Click

    15 <section id="GUID-39D2064D-AD24-4785-956F-18A0CAD57B81"><title>Description</title> <p>The example describes the global message queue. The following

    16 on the following link to download the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-d72e85ad-4659-4f66-9cb3-f084e9505709.zip" scope="external">MessageQueueExample.zip</xref>.</p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-d72e85ad-4659-4f66-9cb3-f084e9505709.html" scope="peer">browse</xref> to view the example code.</p> </section>

    16 sections provide more information. </p> <p><b> MessageQueueExample</b> </p> <p>The example comprises two processes: a Collector, which

    17 <section id="GUID-39D2064D-AD24-4785-956F-18A0CAD57B81"><title>Description</title> <p>The

    17 collects words from the user via the console, and an Inverter, which

    18 example describes the global message queue. The following sections provide

    18 periodically reverses the order of the collected words. The Collector

    19 more information. </p> <p><b> MessageQueueExample</b> </p> <p>The example

    19 and the Inverter pass words to each other using two message queues:

    20 comprises two processes: a Collector, which collects words from the user via

    20 InverterInQ and InverterOutQ. The Collector is the main process which

    21 the console, and an Inverter, which periodically reverses the order of the

    21 starts the Inverter process. The Collector process takes user input

    22 collected words. The Collector and the Inverter pass words to each other using

    22 in form of different words and sends to the Inverter process via message

    23 two message queues: InverterInQ and InverterOutQ. The Collector is the main

    23 queue. The Inverter process receives messages at a regular interval

    24 process which starts the Inverter process. The Collector process takes user

    24 of 10 seconds, inverts the words in the message and sends it back

    25 input in form of different words and sends to the Inverter process via message

    25 to the Collector. </p> <p>The Collector creates an active object to

    26 queue. The Inverter process receives messages at a regular interval of 10

    26 collect words from the user and another active object to receive words

    27 seconds, inverts the words in the message and sends it back to the Collector. </p> <p>The

    27 from the Inverter. Each active object has its own console for display.

    28 Collector creates an active object to collect words from the user and another

    28 More information about running the example is given in the build section

    29 active object to receive words from the Inverter. Each active object has its

    29 of this document. </p> <p><b>Design</b> </p> <p>The following block

    30 own console for display. More information about running the example is given

    30 diagram describes the example in more detail. </p> <fig id="GUID-27A0C389-EDDD-5E17-82EE-2727F21803AF">

    31 in the build section of this document. </p> <p><b>Design</b> </p> <p>The following

    31 <image href="GUID-CD7F507C-CDD5-5612-BA1B-72641D28FA4A_d0e254198_href.png" placement="inline"/>

    32 block diagram describes the example in more detail. </p> <fig id="GUID-27A0C389-EDDD-5E17-82EE-2727F21803AF">

    32 </fig><p><filepath>CCollector.exe</filepath> is the Collector process.

    33 <image href="GUID-CD7F507C-CDD5-5612-BA1B-72641D28FA4A_d0e257906_href.png" placement="inline"/>

    33 The user starts the Collector and creates an active scheduler and

    34 </fig><p><filepath>CCollector.exe</filepath> is the Collector process. The

    34 two global message queues. It also starts the Inverter process called <filepath>Inverter.exe</filepath>. The Collector creates one active object

    35 user starts the Collector and creates an active scheduler and two global message

    35 to collect words from the user and another active object to monitor

    36 queues. It also starts the Inverter process called <filepath>Inverter.exe</filepath>.

    36 its input queue (InverterOutQ). The active object to collect words

    37 The Collector creates one active object to collect words from the user and

    37 is an object of class CCollector and the active object which monitors <codeph>InverterOutQ</codeph> is an object of class <xref href="GUID-A39BC295-2845-3018-B8B8-49418277E7EB.dita"><apiname>CMsgQActive</apiname></xref>. The two active objects have different consoles (one for user input

    38 another active object to monitor its input queue (InverterOutQ). The active

    38 and one for displaying the output message). </p><p> The user inputs

    39 object to collect words is an object of class CCollector and the active object

    39 words in the console. The set of words goes to the <codeph>InverterInQ</codeph> when the "<codeph>Enter</codeph>" key is pressed. If the "<codeph>ESC</codeph>" key is pressed, the system stops and sends the command

    40 which monitors <codeph>InverterOutQ</codeph> is an object of class <xref href="GUID-A39BC295-2845-3018-B8B8-49418277E7EB.dita"><apiname>CMsgQActive</apiname></xref>.

    40 to the Inverter process to stop.</p><p> The Inverter is another process

    41 The two active objects have different consoles (one for user input and one

    41 which opens the global message queues. It creates an active scheduler

    42 for displaying the output message). </p><p> The user inputs words in the console.

    42 and implements a periodic timer. The timer wakes every 10 seconds

    43 The set of words goes to the <codeph>InverterInQ</codeph> when the "<codeph>Enter</codeph>"

    43 to receive the words from the <codeph>InverterInQ</codeph>. It also

    44 key is pressed. If the "<codeph>ESC</codeph>" key is pressed, the system stops

    44 checks for a stop command, which closes the message queue and the

    45 and sends the command to the Inverter process to stop.</p><p> The Inverter

    45 two process. The Inverter inverts the received words and sends the

    46 is another process which opens the global message queues. It creates an active

    46 result to <codeph>InverterOutQ</codeph>. </p><p>In the Collector process,

    47 scheduler and implements a periodic timer. The timer wakes every 10 seconds

    47 the active object that monitors the <codeph>InveterOutQ</codeph> opens

    48 to receive the words from the <codeph>InverterInQ</codeph>. It also checks

    48 the message queue, receives the received words and displays  them

    49 for a stop command, which closes the message queue and the two process. The

    49 in its console. It uses the <xref href="GUID-22E24B08-175B-3446-9D48-9AC4B1663E35.dita"><apiname>NotifyDataAvailable(TRequestStatus&amp;)</apiname></xref> API to monitor the queue for the next set of data. </p><p>The Class diagram of the example is shown below </p><fig id="GUID-E93EF1D6-1B9D-4C76-80B0-1FF660B5C75A">

    50 Inverter inverts the received words and sends the result to <codeph>InverterOutQ</codeph>. </p><p>In

    50 <image href="GUID-3560E862-CB68-584F-B9B6-FCD9F0D202DC_d0e254247_href.png" placement="inline"/>

    51 the Collector process, the active object that monitors the <codeph>InveterOutQ</codeph> opens

    52 the message queue, receives the received words and displays  them in its console.

    53 It uses the <xref href="GUID-6E6B3CD0-FB61-336D-9357-2FFBE3F7A57A.dita"><apiname>NotifyDataAvailable()</apiname></xref> API to monitor the queue

    54 for the next set of data. </p><p>The Class diagram of the example is shown

    55 below </p><fig id="GUID-E93EF1D6-1B9D-4C76-80B0-1FF660B5C75A">

    56 <image href="GUID-3560E862-CB68-584F-B9B6-FCD9F0D202DC_d0e257954_href.png" placement="inline"/>

    58 <section id="GUID-86B04D06-7046-49BD-AE1A-57D5E406F864"><title>Class summary</title><ul>

    52 <section id="GUID-86B04D06-7046-49BD-AE1A-57D5E406F864"><title>Class

    53 summary</title><ul>

    61 <li><p><xref href="GUID-9DD1EA2B-DC59-315C-8E9C-CE6D9461B695.dita"><apiname> RProcess</apiname></xref>A handle to a process.</p></li>

    56 <li><p><xref href="GUID-9DD1EA2B-DC59-315C-8E9C-CE6D9461B695.dita"><apiname> RProcess </apiname></xref> - A handle to a process.</p></li>

    62 <li><p><xref href="GUID-067293BF-B28C-3CEC-92F4-1351A795EA7F.dita"><apiname> CActive</apiname></xref> - The core class of the active object abstraction.</p></li>

    57 <li><p><xref href="GUID-067293BF-B28C-3CEC-92F4-1351A795EA7F.dita"><apiname> CActive</apiname></xref> - The core class of the active

    58 object abstraction.</p></li>

    64 <section id="GUID-F8D41313-760D-417E-834C-09D41F4EDB06"><title>Build</title> <p>The <xref href="GUID-3100800B-B2F7-50EF-BD4C-3C345ECCB2A5.dita">Symbian build

    60 <section id="GUID-F8D41313-760D-417E-834C-09D41F4EDB06"><title>Build</title> <p>The <xref href="GUID-3100800B-B2F7-50EF-BD4C-3C345ECCB2A5.dita">Symbian

    65 process</xref> describes how to build this example application. </p> <p>The

    61 build process</xref> describes how to build this example application. </p> <p>The example builds an executable called <filepath>Inverter.exe</filepath> and <filepath>Collector.exe</filepath> in the standard locations. </p> <p>To run the example, first build <filepath>Inverter.exe</filepath> and start <filepath>Collector.exe</filepath> from the file system

    66 example builds an executable called <filepath>Inverter.exe</filepath> and <filepath>Collector.exe</filepath> in

    62 or from your IDE. After launching the .exes (and depending on the

    67 the standard locations. </p> <p>To run the example, first build <filepath>Inverter.exe</filepath> and

    63 emulator you are using) you may need to navigate away from the application

    68 start <filepath>Collector.exe</filepath> from the file system or from your

    64 launcher or shell screen to view the console. </p> <p>A message input

    69 IDE. After launching the .exes (and depending on the emulator you are using)

    65 console is used for user input and an output message console is used

    70 you may need to navigate away from the application launcher or shell screen

    66 to display inverted words. The output message console that is displayed

    71 to view the console. </p> <p>A message input console is used for user input

    67 at startup. The user can switch between two consoles by <cmdname>Ctrl+Shift+Alt+t </cmdname> combination. </p> <p>The input message console is used to input

    72 and an output message console is used to display inverted words. The output

    68 words. A user presses enter to send the words to the Inverter and

    73 message console that is displayed at startup. The user can switch between

    69 presses <cmdname>ESC</cmdname> to exit the application. When a user

    74 two consoles by <cmdname>Ctrl+Shift+Alt+t </cmdname> combination. </p> <p>The

    70 presses "Enter" the words go to the <codeph>InverterInQ</codeph>.

    75 input message console is used to input words. A user presses enter to send

    76 the words to the Inverter and presses <cmdname>ESC</cmdname> to exit the application.

    77 When a user presses "Enter" the words go to the <codeph>InverterInQ</codeph>.

    79 of 10 secs and inverts the words which it sends to the collector via <codeph>InverterOutQ</codeph>.

    72 of 10 secs and inverts the words which it sends to the collector via <codeph>InverterOutQ</codeph>. The Collector opens the <codeph>InverterOutQ</codeph> and display the words in the output message console. </p> </section>

    80 The Collector opens the <codeph>InverterOutQ</codeph> and display the words

    81 in the output message console. </p> </section>